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Author Topic: What;'s the Power output of a Car Keyfob ?  (Read 6470 times)

Offline neilep

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What;'s the Power output of a Car Keyfob ?
« on: 16/02/2008 01:14:27 »
Dear All,

D'ya like my car key-fob ?




Nice eh ?


When I was out with the fam the other day we parked the car and we all ended up walking along a raised walkway above the car (say 20 meters up)......and we could see the car about 100 meters away. I thought I'd give the key-fob a push and to my surprise it worked...the cars lights flashed all nice and flashy

How much power is in one of these things and how sensitive is the receiver in the car ?

It is an RF frequency yes ?




 

Offline engrByDayPianstByNight

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What;'s the Power output of a Car Keyfob ?
« Reply #1 on: 16/02/2008 06:57:07 »
Pretty sexy-looking key fob for a minivan.

My guess is on the magnitude of milliwatts, since it transmits a few dozen bits at most,and is expected to be used in short range.

Was it a good day when you used the key fob 100[m] away? Sounds like you had the light-of-sight at the time, and if the weather was good, the signal from your fob transmitter would indeed go pretty far.
 

Offline Karen W.

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What;'s the Power output of a Car Keyfob ?
« Reply #2 on: 16/02/2008 07:10:41 »
Dear All,

D'ya like my car key-fob ?




Nice eh ?


When I was out with the fam the other day we parked the car and we all ended up walking along a raised walkway above the car (say 20 meters up)......and we could see the car about 100 meters away. I thought I'd give the key-fob a push and to my surprise it worked...the cars lights flashed all nice and flashy

How much power is in one of these things and how sensitive is the receiver in the car ?

It is an RF frequency yes ?




Those are cool but I don't know how they work!

Pretty sexy-looking key fob for a minivan.

My guess is on the magnitude of milliwatts, since it transmits a few dozen bits at most,and is expected to be used in short range.

Was it a good day when you used the key fob 100[m] away? Sounds like you had the light-of-sight at the time, and if the weather was good, the signal from your fob transmitter would indeed go pretty far.

How did you know it was a mini van he was driving?? He did not say that! LOL....OOOOOHHH OOOOOOHHHHH.....LOL!
 

Offline Karen W.

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What;'s the Power output of a Car Keyfob ?
« Reply #3 on: 16/02/2008 07:12:38 »
The ones I have seen here in the states work from very long distances and they work very well weather good or not! I think they are great ideas and a great safety precaution!
 

Offline DoctorBeaver

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What;'s the Power output of a Car Keyfob ?
« Reply #4 on: 16/02/2008 08:10:35 »
It'll work over even greater distance if you hold it against your temple when you use it. This was tested on Top Gear and the presenters were stunned that it's true.
 

Offline neilep

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What;'s the Power output of a Car Keyfob ?
« Reply #5 on: 16/02/2008 15:32:13 »
Pretty sexy-looking key fob for a minivan.

My guess is on the magnitude of milliwatts, since it transmits a few dozen bits at most,and is expected to be used in short range.

Was it a good day when you used the key fob 100[m] away? Sounds like you had the light-of-sight at the time, and if the weather was good, the signal from your fob transmitter would indeed go pretty far.

LOL...actually it's a Reliant Robin !

It was evening and yes I did have line of sight and was inside. The weather had been a good day!

THANK EWE engrByDayPianstByNight
 

Offline neilep

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What;'s the Power output of a Car Keyfob ?
« Reply #6 on: 16/02/2008 15:35:36 »
The ones I have seen here in the states work from very long distances and they work very well weather good or not! I think they are great ideas and a great safety precaution!

Unless you car automatically locks itself again there is always the danger of accidentally pressing the buttons and opening the car eh ?
 

Offline neilep

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What;'s the Power output of a Car Keyfob ?
« Reply #7 on: 16/02/2008 15:36:16 »
It'll work over even greater distance if you hold it against your temple when you use it. This was tested on Top Gear and the presenters were stunned that it's true.

Hmmmmmmmmmmm ??....Is the good doctor serious ?...or not ?.....YOU decide !!
 

paul.fr

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What;'s the Power output of a Car Keyfob ?
« Reply #8 on: 16/02/2008 15:57:19 »
It'll work over even greater distance if you hold it against your temple when you use it. This was tested on Top Gear and the presenters were stunned that it's true.

Hmmmmmmmmmmm ??....Is the good doctor serious ?...or not ?.....YOU decide !!

It is correct, i was going to post this as a kitchen science ages back...but forgot! Maybe the Doc could do the honours.
 

Offline engrByDayPianstByNight

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What;'s the Power output of a Car Keyfob ?
« Reply #9 on: 16/02/2008 17:00:12 »
Pretty sexy-looking key fob for a minivan.

My guess is on the magnitude of milliwatts, since it transmits a few dozen bits at most,and is expected to be used in short range.

Was it a good day when you used the key fob 100[m] away? Sounds like you had the light-of-sight at the time, and if the weather was good, the signal from your fob transmitter would indeed go pretty far.

How did you know it was a mini van he was driving?? He did not say that! LOL....OOOOOHHH OOOOOOHHHHH.....LOL!

It's the figure on the middle button of the key fob, plus the fact that neilep said he was out with his family, that made me venture a guess and to see if I could perhaps get a "Wow" from someone. Thanks for playing along, Karen. :-)
 

Offline Pumblechook

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What;'s the Power output of a Car Keyfob ?
« Reply #10 on: 16/02/2008 18:58:26 »
Probably around one milliwatt.   The receivers in cars are a bit crude.  I have known transmitters of around 1 mW reach 150 km or more with good aerials at both ends and a sensitive receiver.
« Last Edit: 16/02/2008 22:11:12 by Pumblechook »
 

Offline Karen W.

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What;'s the Power output of a Car Keyfob ?
« Reply #11 on: 16/02/2008 19:13:43 »
Pretty sexy-looking key fob for a minivan.

My guess is on the magnitude of milliwatts, since it transmits a few dozen bits at most,and is expected to be used in short range.

Was it a good day when you used the key fob 100[m] away? Sounds like you had the light-of-sight at the time, and if the weather was good, the signal from your fob transmitter would indeed go pretty far.

How did you know it was a mini van he was driving?? He did not say that! LOL....OOOOOHHH OOOOOOHHHHH.....LOL!

It's the figure on the middle button of the key fob, plus the fact that neilep said he was out with his family, that made me venture a guess and to see if I could perhaps get a "Wow" from someone. Thanks for playing along, Karen. :-)

Lol.... yes I figured.... LOL...My oooooh  comment was implying the Twilight Zone music but me is no so good at back ground noise sound when I have to try to spell them!!!  ;)
« Last Edit: 16/02/2008 19:21:50 by Karen W. »
 

Offline Karen W.

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What;'s the Power output of a Car Keyfob ?
« Reply #12 on: 16/02/2008 19:39:33 »
The ones I have seen here in the states work from very long distances and they work very well weather good or not! I think they are great ideas and a great safety precaution!

Unless you car automatically locks itself again there is always the danger of accidentally pressing the buttons and opening the car eh ?
I guess so, but I was thinking on the lines of personal safety....it avoids fumbling to open the car quickly instead of standing in a dark parking lot at night trying to unlock your car.... which sometimes makes you a target  to preditors, so being able to have it open before you get to it could be a nice safety measure depending on the situation!!    I would like to have  that feature available on my car!
 

Offline Pumblechook

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What;'s the Power output of a Car Keyfob ?
« Reply #13 on: 17/02/2008 11:03:28 »
We all point the fob at the car but as it is an RF device and not infrared or  ultrasonic or a laser we dont need to.
 

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What;'s the Power output of a Car Keyfob ?
« Reply #13 on: 17/02/2008 11:03:28 »

 

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